Machines for extracting coffee from a capsule or from a pod containing compressed coffee powder are known. Also known are machines for extracting coffee from a filter containing ground coffee and able to be filled manually.
These machines comprise a water tank, a pump and a heating means, for example a boiler, for heating the water to a temperature of about 90° C., suitable for extraction of the coffee.
When the water reaches the required temperature, the heating means are automatically switched off and the user may activate dispensing of the coffee, by means of a pushbutton which discharges a measured amount of water into the capsule (pod) or into the filter containing the ground coffee. The hot water penetrates into the capsule through a capsule holder or a filter holder for the ground coffee and extracts the liquid coffee.
Machines which use capsules (pods) are popular because the coffee is already prepared in a measured amount and compressed, thus avoiding the need for the user to fill the coffee manually and greatly speeding up preparation thereof. Also the machine emptying operation is simplified, since the user merely has to remove the capsule and does not have to clean or wash the machine once the coffee has been dispensed.
However, machines which use capsules (pods) are not very versatile because they do not allow the preparation of coffee in different concentrations, for example the preparation of both espresso coffee and Americano coffee.
Moreover, both machines which use capsules (pods) and manual filter machines have major drawbacks associated with the method of heating the water.
A first drawback consists in the long machine heating time and the consequent long wait before dispensing occurs, this being necessary in order to heat all the water inside the boiler to the correct temperature for extraction of the coffee (about 90° C.).
A second drawback relates to the impossibility of precisely regulating the temperature of the water.
In fact, the heating means are switched off when the water reaches the required temperature. However, after switching off, it may happen that the user does not perform immediately dispensing of the coffee and that the water inside the boiler cools down again.
In order to prevent the coffee from being prepared with water which is too cold, it is known to sense constantly the temperature of the water inside the boiler and to activate again the heating means in order to heat up the water again. However, between switching off and subsequent switching on again of the heating means, the temperature of the water is subject to fluctuations which affect the quality of the coffee dispensed.
Moreover, frequent switching on and off of the heating means results in wasted energy. The amount of wasted energy is considerable because all the water inside the boiler must be heated again.
On the other hand, in order to avoid the temperature fluctuations, it is not sufficient to keep the heating means always switched on or to set a long standby time, for example of 10 minutes, before they switch off; these solutions in fact further increase the amount of wasted energy.
Finally, even performing dispensing of the water as soon as the machine has reached the required temperature—namely, assuming use of the machine in the most efficient manner possible—does not guarantee that the temperature of the water is correct. In fact it happens that dispersion of heat along the fluid path which conveys the water from the boiler to the capsule (pod) or the filter influences the temperature.
In an attempt to overcome this further drawback, in the known machines it is envisaged raising the temperature of the water inside the boiler to a value T2 higher than the temperature T1 required during dispensing, for example to T2=98° C. instead of T1=90° C., thus compensating for the losses of heat along the fluid path.
However, it is not possible to predict exactly the loss of heat along the path, for example as a result of the ambient temperature, which influences dispersion. Also the water present in the boiler, which may consist of one or more liters, may cause sudden heat dispersion or sudden changes in temperature, which furthermore may be differently sensed in different portions of the boiler.
It thus happens that the water reaches the capsule (pod) or the manual filter too hot or too cold, preventing correct extraction of the coffee.
In other words, even if the known coffee machines are programmed to prevent the dispensing of water before a preset temperature is reached, and avoid the incorrect extraction of the coffee with water which is too cold, they are unable to avoid long waiting times for the user, prevent temperature fluctuations and achieve savings in electric power.
The technical problem forming the basis of embodiments of the present invention is that of devising a coffee machine using pods, capsules or a manual filter able to: heat rapidly the temperature of the water, thus reducing the waiting times for the coffee; raise the temperature of the water to a preset optimum value for extraction of the coffee from the pod, capsule or manual filter, and maintain this temperature for a long time, in order to obtain a short coffee, espresso, Americano coffee or a coffee of a different type of quality and superior taste, but also reduce substantially the energy consumption, thus overcoming all the drawbacks which hitherto are associated with the known machines.